Conventionally, an inkjet recording apparatus, which ejects ink from a recording head to a recording medium and attaches the ink onto the medium, thereby performing the recording, has been known in the market.
In this conventional apparatus, a carriage to which the recording head is mounted reciprocates in a scanning direction, while the recording medium, such as a sheet of paper, is transferred in a direction perpendicular to the scanning direction. Positions of the recording head and the recording paper, as well as the ejection of the ink from the head, are controlled, so that the ink is attached to a specified position on the recording paper for recording. In this apparatus, a carriage driving motor, as a driver, reciprocates the carriage in the scanning direction, while a transfer motor, as a driver, transfers the recording paper in a transfer direction.
High speed recording is demanded for the inkjet recording apparatus, while downsizing the apparatus is also required. For realizing the high speed recording, the carriage and the recording paper must move at high speed. For instance, it is desirable to employ a high-power carriage driving motor and a high-power transferring motor. However, the high-power motor needs a larger outer diameter or a longer length along a rotating axis, so that a size of the motor is necessarily be bulky.
On the other hand, on a transfer path of the recording paper or in a travel space where the carriage reciprocates, no components should be placed. Thus, these motors must be placed outside of the transfer path and travel space, and a large additional space must be provided for disposing these motors. As a result, high-speed recording is achieved at the cost of increasing the size of the apparatus.
As such, the inkjet recording apparatus has encountered contradictory requirements, i.e., high-speed recording and downsizing.
Isn order to solve the problem of these contradictory requirements, the following structure is designed. The carriage and an ink-tank are coupled to each other with ink supplying tubes, and the ink-tank is disposed outside of the carriage. Ink in the ink-tank is supplied to recording heads of the carriage via the tubes. However, even for an apparatus with this structure, it is very difficult to dispose the tubes so that the ink can be supplied in a stable manner for recording at high-speed, e.g., ink ejecting frequency is not less than 18 kHz.
When these tubes are bent with a curvature as small as an electric wiring can be bent, the flowing path is bent and damaged. The smaller the diameter of the tube, the smaller the curvature that the tube can be bent. However, the resistance in the flowing path against the ink increases due to narrowing the diameter of the tube.
Therefore, these tubes are desirably disposed with rather larger curvatures, which, however, requires a larger space and results in a bulky apparatus.
Even if the tubes are disposed with rather larger curvatures, the carriage is placed at a distance from the ink-tank, so that the tubes must be long. This results in greater resistance from the flow-path against the flowing ink, so that the ink cannot be supplied in a stable manner. In addition to this, the distant placing of the ink-tank from the carriage invites a bulky apparatus. Further, narrower and longer tubes yield a greater flow path resistance against the flowing ink, which prevents high-speed printing.